1. Field of the Invention
The present invention is directed to a medical implant and to a method for the control of the medical implant, such as an insulin pump, a heart pacemaker or a defibrillator.
2. Description of the Prior Art
It is known to wirelessly communicate with a medical implant by means of an external programming unit. This ensues, for example, using radio signals. Various settings for the implant can be modified and influenced with the programming unit. Given an insulin pump, it is desirable to be able to modify the dose that is to be administered and the point in time for the administration of the dose and to interrupt a dose that has been started. Given a heart pacemaker, one may modify the stimulation frequency, the thresholds of sampled values and may change the stimulation mode of the heart pacemaker, etc. Given a defibrillator, one may, for example, activate various operating modes. Another important task of the programming unit is to provide the possibility of taking information from the implant. This can be an overview of the signals sensed by the implant.
U.S. Pat. No. 5,113,859 discloses a device for bi-directional (duplex) communication between two modules that, according to one embodiment, are arranged respectively in an implant or in an external programming unit. The communication ensues acoustically with ultrasound signals that are generated by piezocrystals. During the transmission, the crystal is activated by a carrier wave modulated by information. Transmission and reception units are provided both in the implant and in the programming unit. The transmission unit includes an oscillator that generates a sine signal that is used a carrier wave having a carrier wave frequency that lies within the range of 10 Khz through 100 Khz. The oscillator is coded by a pulse signal such that the resultant signal that is communicated to the piezocrystal is composed of bursts of oscillations, with the number of oscillations in every burst being varied according to the coding employed. Provided in every reception unit are a filter, a demodulator and a pulse-shaping unit that restores the pulses, and thus the information that has been transmitted. The apparatus disclosed in U.S. Pat. No. 5,113,859 can be employed to modify various parameters in a heart pacemaker or in a defibrillator or in an implant that is provided for administering a medication. In order to influence the implant disclosed in U.S. Pat. No. 5,113,859, consequently, it is necessary that an external programming unit be used.
Implanted insulin pumps, for example, can be programmed in order to administer a specific quantity of insulin, referred to as a basal flow, with increased insulin doses on certain occasions, often in combination with meals. A further possibility is that the patient himself defines the so-called mealtime doses with a programming unit, by means of which the insulin pump is commanded at self-selected points in time to emit an increased dose with a dose volume that can be selected. This yields greater flexibility for the patient but also means the programming unit must always be carried by the patient. A further disadvantage is that there can be instances when the patient considers it unpleasant or laborious to take out the programming unit in order to administer an insulin dose. For example, this can be at the beach, when visiting a restaurant or some other place where there are many people.